Muffler inserts of this type are located in the mufflers of the exhaust units of combustion engines for noise damping. Usually the mufflers are cup-like structures, through which the exhaust pipe is guided, and in which sound can spread out and be lost in the damping material.
The sound absorbing material preferably is a so-called porous sound absorbing material, therefore a material without structured arrangements of cavities and material process.
Such materials have to be inserted into the muffler cups. It is well known how to release these materials from a container as a kind of refilling and to insert them into muffler cups. This has a number of disadvantages, since it does not permit the amount to be inserted to be determined exactly and provide a uniformly loose amount. In addition it has been shown that the service life of such materials is extremely short.
In DE G 89 10 785 it was proposed that a cylindrical muffler insert element be made out of inner and outer screen pipe with a filled intermediate space. This is expensive to produce, transport, store, and assemble. In addition no exact seating in the muffler cup is produced, so that the effect is not satisfactory.
From DE 36 42 714 A1 it is known how to push insulation from shaped fiber parts in the form of a flexible tube onto exhaust lines. In this case several metal film and fiberglass hose layers are combined into a shaped part.
DE 31 44 193 discloses a sound-absorbing body of a mineral fiber tube shell. In the first place this is a matter of a bonded material, therefore a shaped piece bonded with a binding agent, the effect of which is unsatisfactory and the service life of which is short. In addition, the production and assembly are expensive and the shaped part is expensive.
From DE G 91 01 926 it is known how to prepare a damping material shaped part in the form of a cushion. In this case the long sides are sewed up, which produces a material shrinkage. A cavity, which leads to the formation of heat centers, arises in the case of locating the cushion in a muffler housing. These lead to premature sealing of the muffler insert.
Altogether the muffler inserts known from the prior art have the disadvantage that they are either poorly damping, rigid and solid bodies, or in the case of the design as light accumulations at the time of production, the assembly and the use are problematic. Altogether the inserts known from the prior art lead to a frequent need for replacement and thus are uneconomical.